Chromophores are molecules that selectively transmit and absorb color by virtue of their possession of certain chemical groups (e.g., nitrite(—NO2), diazo(—N═N—), triphenylmethane, quinoneimine, xanthene, anthraquinone, or the like). The color of a chromophore is created by an electronic transition between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital LUMO) present in the chromophore following absorption of incoming light. Due to their possession of color, chromophores can be employed in a wide variety of diverse applications. For instance, chromophores can be employed as “labels” or a means of detection, for example, in diagnostic applications, forensics applications, laboratory studies, and the like. More recently, chromophores have been employed in the telecommunications industry, for example, to convert light into electrical current (Shi et al., Science, 288, 119–122 (April 2000)), as components of a multifunctional optical switch or waveguide (e.g., U.S. Ser. No. 09/357,201 and PCT/US00/19921), and for other uses.
These more recent applications, e.g., as an optical waveguide or switch, use a chromophore to change or add optical properties by modifying the backbone of a polymer. However, addition of a chromophore to molecules other than polymers is well known and has been described in the and Modification of a polymer backbone, and particularly a polyimide backbone with different chromophores also is known in the art, and is described, for instance, in Marder et al., Nature, 388, 845–851 (1997); Saaedeh et al., “Polyimides with a Diazo Chromophore Exhibiting High Thermal Stability and Large Electrooptic Coefficients”, Macromolecules, 30 (18), 5403–5407 (1997); Yu et al., “Novel Second-Order Nonlinear Optical, Aromatic and Aliphatic Polyimides Exhibiting High-Temperature Stability”, Applied Physics Letters, 66, 1050–1052 (1995); Yu et al., “Novel Second-Order Nonlinear Optical Polyimides,” Society of Photooptical Instrumentation Engineers, 2527, 127–136; U.S. Ser. No. 09/357,201; and
PCT/US00/19921). These modifications expand the responsiveness of the polyimide to different wavelengths of light Chromophoric compounds suitable for use as an optical waveguide or switch optimally have a low dielectric constant and include for instance, those described in U.S. Pat. No. 5,318,729; U.S. Ser. No. 09/357,201;PCT/US00/19921, and by Moylan et al. J. Am. Chem. Soc. 115, 12599–12600 (1993); Polymers for Second-Order Nonlinear Optics, ACS Symposium Series 601, 66, (1995); and Miller et al. Chem. Mater., 6,1023–1032(1994). Despite the existence of these few compounds, a considerably larger inventory of photonic materials, preferably which exhibit second-order nonlinear optical (2o-NLO) properties, and optimally which have a low dielectric constant, are needed to meet the increasingly sophisticated demands of the telecommunications industry. The provision of further chromophores, especially 2o-NLO chromophores, would increase the availability of novel, useful photonic materials. Optionally such further chromophores also can be employed for other applications, e.g., as labels in applications outside the telecommunications industry.
The present invention accordingly provides novel chromophores. Preferably these chromophores exhibit 2o-NLO properties. Optimally such chromophores can be employed in optical switches (particularly as described in U.S. Ser. No. 09/357,201, and PCT/US00/19921, incorporated by reference) that can perform several critical tasks for the telecommunications industry—e.g., wavelength division multiplexing, wavelength division demultiplexing, performance as an add/drop filter and/or interconnect device. These and other objects and advantages of the present invention, as well as additional inventive features, will be apparent from the following description of the invention provided herein.